PHANGS–JWST First Results: Measuring Polycyclic Aromatic Hydrocarbon Properties across the Multiphase Interstellar Medium

Chastenet, Jérémy; Sutter, Jessica; Sandström, Karin; Belfiore, Francesco; Egorov, Oleg V.; Larson, Kirsten L.; Leroy, Adam K.; Liu, Daizhong; Rosolowsky, Erik; Thilker, David A.; Watkins, Elizabeth J.; Schwarz, Greg J.; Barnes, Ashley; Bigiel, Frank; Boquien, M.; Chevance, Mélanie; Dale, Daniel A.; Kruijssen, J. M. Diederik; Emsellem, Éric; Grasha, Kathryn; Groves, Brent; Hassani, Hamid; Hughes, Annie; Kreckel, Kathryn; Meidt, Sharon E.; Pan, Hsi-An; Schinnerer, E.; Whitcomb, Cory M.

doi:10.3847/2041-8213/acac94

Cited by 25 publications

(25 citation statements)

References 61 publications

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“…The attenuation-only regions could be explained in multiple ways. As noted above, the dust temperature distribution, but also grain size distribution and PAH fraction (Chastenet et al 2023a, this Issue, Chastenet et al 2023b, this Issue, Dale et al 2023, this Issue, Egorov et al 2023 this Issue), can influence the degree to which the MIRI bands are a complete tracer of the dust distribution. Some attenuation-only regions also lie in false negatives for MIR dust emission on the scale of interest or lie in relatively MIR-faint, intermediate-surface-brightness regions of the visible galaxy disk.…”

Section: Contrasting Views Of the Dust Filament Networkmentioning

confidence: 91%

PHANGS–JWST First Results: The Dust Filament Network of NGC 628 and Its Relation to Star Formation Activity

Thilker

Lee

Deger

et al. 2023

ApJL

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PHANGS–JWST mid-infrared (MIR) imaging of nearby spiral galaxies has revealed ubiquitous filaments of dust emission in intricate detail. We present a pilot study to systematically map the dust filament network (DFN) at multiple scales between 25 and 400 pc in NGC 628. MIRI images at 7.7, 10, 11.3, and 21 μm of NGC 628 are used to generate maps of the filaments in emission, while PHANGS–HST B-band imaging yields maps of dust attenuation features. We quantify the correspondence between filaments traced by MIR thermal continuum/polycyclic aromatic hydrocarbon (PAH) emission and filaments detected via extinction/scattering of visible light; the fraction of MIR flux contained in the DFN; and the fraction of H ii regions, young star clusters, and associations within the DFN. We examine the dependence of these quantities on the physical scale at which the DFN is extracted. With our highest-resolution DFN maps (25 pc filament width), we find that filaments in emission and attenuation are cospatial in 40% of sight lines, often exhibiting detailed morphological agreement; that ∼30% of the MIR flux is associated with the DFN; and that 75%–80% of the star formation in H ii regions and 60% of the mass in star clusters younger than 5 Myr are contained within the DFN. However, the DFN at this scale is anticorrelated with looser associations of stars younger than 5 Myr identified using PHANGS–HST near-UV imaging. We discuss the impact of these findings on studies of star formation and the interstellar medium, and the broad range of new investigations enabled by multiscale maps of the DFN.

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Section: Contrasting Views Of the Dust Filament Networkmentioning

confidence: 91%

PHANGS–JWST First Results: The Dust Filament Network of NGC 628 and Its Relation to Star Formation Activity

Thilker

Lee

Deger

et al. 2023

ApJL

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“…Egorov et al (2023) analyze the F1130W/F770W parameter, widely considered to be a tracer of the ratio of neutral to ionized PAHs (Draine & Li 2001;Maragkoudakis et al 2020), in H II regions in NGC 628, NGC 1365, NGC 7496, and IC 5332 and find lower values of F1130W/F770W in regions with higher [S III]/[S II] ratios, indicating harder radiation fields. Chastenet et al (2023) probe PAH band ratios across the disks of the four galaxies and find evidence of hotter, highly ionized PAHs in the vicinity of H II regions that are defined by the radiation from young stars. Finally, Sandstrom et al (2023) create maps of PAH band ratios in the same three galaxies considered in this work and find fairly flat F335M PAH /F1130W radial profiles, with amplitudes similar to what we find (0.07-0.24 in νf ν units).…”

Section: Notesmentioning

confidence: 99%

PHANGS–JWST First Results: The Influence of Stellar Clusters on Polycyclic Aromatic Hydrocarbons in Nearby Galaxies

Dale

Boquien

Barnes

et al. 2023

ApJL

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We present a comparison of theoretical predictions of dust continuum and polycyclic aromatic hydrocarbon (PAH) emission with new JWST observations in three nearby galaxies: NGC 628, NGC 1365, and NGC 7496. Our analysis focuses on a total of 1063 compact stellar clusters and 2654 stellar associations previously characterized by the Hubble Space Telescope in the three galaxies. We find that the distributions and trends in the observed PAH-focused infrared colors generally agree with theoretical expectations, and that the bulk of the observations is more aligned with models of larger, ionized PAHs. These JWST data usher in a new era of probing interstellar dust and studying how the intense radiation fields near stellar clusters and associations play a role in shaping the physical properties of PAHs.

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“…Our results show variations of the ratio between 0.02 and 0.08, with an average value of ∼0.05 across the three targets. These ratios are investigated in more detail in Chastenet et al (2023) and Dale et al (2023). For comparison, we plot two ratios from the Draine et al (2021) models.…”

Section: Pah-to-continuum Ratiosmentioning

confidence: 99%

“…These targets have deep, high-resolution, ancillary information from the Atacama Large Millimeter/submillimeter Array (Leroy et al 2021), Very Large Telescope-MUSE (Emsellem et al 2022), Hubble (Lee et al 2022), AstroSat (H. Hassani et al 2023, in preparation), and more. Combining NIRCam imaging of the 3.3 μm PAH feature with MIRI imaging of the 7.7 and 11.3 μm features enables one of the first studies of the variation of both PAH size and charge over large regions of nearby galaxies (Chastenet et al 2023), in HII regions (Egorov et al 2023), and near young star clusters and associations (Dale et al 2023;Rodriguez et al 2023). As part of this effort, we found it was necessary to adjust the current best NIRCam medium-band continuum removal prescription in the literature from Lai et al (2020) to account for PAHemission (or related dust-emission) contamination of F360M filter (Section 3).…”

Section: Introductionmentioning

confidence: 99%

PHANGS–JWST First Results: Mapping the 3.3 μm Polycyclic Aromatic Hydrocarbon Vibrational Band in Nearby Galaxies with NIRCam Medium Bands

Sandström¹,

Chastenet

Sutter

et al. 2023

ApJL

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We present maps of the 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission feature in NGC 628, NGC 1365, and NGC 7496 as observed with the Near-Infrared Camera imager on JWST from the PHANGS–JWST Cycle 1 Treasury project. We create maps that isolate the 3.3 μm PAH feature in the F335M filter (F335MPAH) using combinations of the F300M and F360M filters for removal of starlight continuum. This continuum removal is complicated by contamination of the F360M by PAH emission and variations in the stellar spectral energy distribution slopes between 3.0 and 3.6 μm. We modify the empirical prescription from Lai et al. to remove the starlight continuum in our highly resolved galaxies, which have a range of starlight- and PAH-dominated lines of sight. Analyzing radially binned profiles of the F335MPAH emission, we find that between 5% and 65% of the F335M intensity comes from the 3.3 μm feature within the inner 0.5 r 25 of our targets. This percentage systematically varies from galaxy to galaxy and shows radial trends within the galaxies related to each galaxy’s distribution of stellar mass, interstellar medium, and star formation. The 3.3 μm emission is well correlated with the 11.3 μm PAH feature traced with the MIRI F1130W filter, as is expected, since both features arise from C–H vibrational modes. The average F335MPAH/F1130W ratio agrees with the predictions of recent models by Draine et al. for PAHs with size and charge distributions shifted toward larger grains with normal or higher ionization.

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PHANGS–JWST First Results: Measuring Polycyclic Aromatic Hydrocarbon Properties across the Multiphase Interstellar Medium

Cited by 25 publications

References 61 publications

PHANGS–JWST First Results: The Dust Filament Network of NGC 628 and Its Relation to Star Formation Activity

PHANGS–JWST First Results: The Dust Filament Network of NGC 628 and Its Relation to Star Formation Activity

PHANGS–JWST First Results: The Influence of Stellar Clusters on Polycyclic Aromatic Hydrocarbons in Nearby Galaxies

PHANGS–JWST First Results: Mapping the 3.3 μm Polycyclic Aromatic Hydrocarbon Vibrational Band in Nearby Galaxies with NIRCam Medium Bands

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